1. Technical Field
This invention relates to a tool profile automatic graphic display system for automatically describing the profile of a tool used when a workpiece is to be machined into a predetermined shape based on a conversational-type machining program using e.g. a computer-controlled NC lathe.
2. Description of the Related Art
In order to fabricate a workpiece having a complex, elaborate structure in cases where the machining is performed by a machine tool such as a cutter, drill or milling machine, positional coordinates are decided using e.g. a keyboard and display, and machining data (a program command tape) for numerical control (NC) are prepared. An NC unit numerically controls the machine tool on the basis of the machining data on the command tape to subject the workpiece to the desired machining.
In machining of this kind, the tools used naturally differ depending upon the type of machining, e.g. drilling and planar machining. Moreover, even for the same planar machining operation, cutting tools of various shapes are prepared and are used accordingly depending upon the shape to which the workpiece is to be cut and the region machined. To facilitate tool selection at such time, a CNC (computer NC) has been developed to enable the programming of NC data in accordance with drawings in a conversational mode of operation while the profile of a workpiece blank and the profile into which the workpiece blank is to be machined are displayed on a graphic display. With an NC unit of this kind, machining data are specified to create the machining program automatically. A list of tools prepared on the machine tool side is created in advance and the tools best suited for the workpiece material or region to be machined are then selected automatically. Since such cutting conditions as revised values of velocity and depth of cut which prevail when a selected tool is driven into operation change, the usual practice is to prepare files of plural cutting conditions, graphically display a tool trajectory in accordance with the file corresponding to the selected tool, and then decide the machining data.
When a machining drawing is complicated, however, the associated cutting requirements change frequently. Consequently, though the operator is capable of freely specifying the tools and regions to be machined, skill is required for such an operation. If it were attempted to decide all of the machining steps automatically by employing a function for such purpose, it would not be possible to check sufficiently for interference between the selected tool and a chuck or tool stock by relying solely upon the graphic display of the tool trajectory. The problem that would result is issuance of an alarm when the NC unit is operated by a machining tape or the like using the machining data that have been prepared.